ADDITIONAL INFORMATION Any information on the system which could not be included in the Handbook for Disk Users will be found in a file on the system disk called `INFO'. To read the information, enter CP/M, type: TYPE INFO and press NEWLINE As the text is shown on the screen, hold down CONTROL and press S to stop and restart the display. How to use this Manual CONTENTS If you just want 1 Introduction ................................................................................ 3 to use prepared READ 2 Connecting up ............................................................................ 9 programs on your SECTIONS 1, 2,3 3 Getting started ........................................................................ 13 NewBrain, and don't 4 NewBrain BASIC with disk-Programs ................................... 25 want to know about LOOK THROUGH 5 NewBrain BASIC with disk-Data Files .................................. 31 how computers work ... SECTIONS 10-12 6 NewBrain BASIC with disk-Random Access Files ............... 41 7 Cataloguing files through BASIC ............................................ 51 8 Using cassettes ....................................................................... 53 If you know some WORK THROUGH THE 9 What is CP/M? ........................................................................ 55 BASIC already and WHOLE OF THIS 10 Working with disks .................................................................. 59 want to develop your MANUAL AS A BASIS 11 Using CP/M with NewBrain .................................................... 78 ability by using FOR FURTHER STUDY 12 Error codes .............................................................................. 82 disk techniques ... OF CP/M METHODS 13 The Expansion Interface Module ........................................... 84 I ndex .............................................................................................. 90 If you know little READ SECTIONS 1, 2,3 of computers or BASIC, but wish LOOK THROUGH to become SECTIONS 10-12 proficient ... WORK THROUGH THE BEGINNER'S GUIDE WORK THROUGH THE REST OF THIS MANUAL 1 Introduction This manual describes how to use the NewBrain microcomputer model A or AD with disk memory. Computers carry out the tasks we give them by following sets of instructions called programs. These may range from a simple program to calculate the wall area of a room to a very large and complex program for word-processing or keeping accounts. When using a program the computer stores it in a temporary memory called RAM (random access memory). The RAM can only hold a program while the computer is switched on. As soon as you switch off, the program disappears, which makes it possible to use many different programs in the same computer, and so to use the same computer for many different tasks. It is necessary, therefore, to have some means of storing programs permanently, so that any program can be `loaded' into the RAM and used at any time. With microcomputers, programs are often stored on cassette tape, which is effective enough, but rather laborious to use: tapes have continually to be re-wound and positioned; records have to be kept of where programs are; and the programs take a relatively long time to load. 2 3 1. Introduction 1. Introduction Disks on the other hand are easy to use; they can store many The disk drive is linked to the computer by the Disk Controller, programs and load them into the computer quickly. The disks used which interprets between the two and controls the operation of the by NewBrain are 5.25in. `floppy' disks, made of mylar coated with a disk drive. magnetic oxide, rather like recording tape. Each disk is permanently enclosed in a black plastic cover. Disks are used in disk drives. The central hole is for the spindle of the drive, which spins the disk at high speed inside its plastic cover. You may also fit an Expansion Interface Module into the system to provide additional memory, which is needed for many business programs, and to enable you to link your NewBrain with other computers and equipment. The small hole is an index mark which enables the disk drive to reference the disk correctly. When the disk is used in the disk drive, its surface is scanned by the 'read-write head' through the long slot in the plastic cover. The whole operation is rather like that of a record player, except that the read-write head works by magnetism. 4 5 1. Introduction 1. Introduction Now disk memory works Earlier in this section we likened disk drives to record players, but there is an important difference in the way the information on disks is organised. With a sound recording, the information is in serial order, just like the information on a tape. But computer disks are organised in such a way that information can be taken from any part of the disk at any time. When a program is recorded onto a disk, it may be spread over several sectors on the same track, or even over more than one track. The computer needs to be able to find this information again and put it all together in the same order. To make this possible, each disk is provided with a `directory' which, like the programs, is magnetically encoded onto the disk, and updated every time a program is added or deleted. The directory is not only used by the computer system; it also serves as a contents list which the user can display on the screen. I nformation recorded on disks can be of several kinds: -programs, which cause the computer to carry out tasks; -text files containing text which will eventually be output to a printer; -data files from which the computer can select information. The general name for any block of data or program on a disk is a `file'. 6 7 1. Introduction Formatting All the organisation of the disk described so far-tracks, sectors If you are using a NewBrain Module Housing, first install your and the directory-is imposed on the disk by a process known as modules in the housing, with the Expansion Interface Module `formatting'. A blank disk as bought from your computer store is (if any) lowest. literally blank, and no files can be recorded onto it until it is placed in a disk drive and formatted. This is done by causing the computer to format the second disk according to the pattern of the fi rst. Before connecting the modules together, check the ribbon cables and connectors. Note that the connectors have a small key notch at the bottom, matching a similar shape in the socket. 9 2. Connecting up 2. Connecting up With Expansion Interface Module Power Supply Unit and Monitor Connect the ribbon cables as shown below. The Power Supply Unit should be connected as shown. Either a monitor or a television set may be used, connecting with the appropriate lead to the marked point at the back of the NewBrain processor. The disk drive has an independent power supply. Without Expansion Interface Module Connect the ribbon cables as shown below. Note that the Disk Controller Module is the other way up compared with the illustration above. 10 11 When you have fully connected up the system, plug into the mains and switch on. There is no separate switch for the NewBrain processor or modules, so these will start to operate immediately, but remember to switch on the disk drive(s) and monitor. What happens next depends on your system. If nothing happens or if you do not get the right message, check all the connections against the diagram in the last section and make sure all plugs are pushed securely home. This starting display, incidentally, is called a menu, because it offers you a choice. Many computer applications are controlled by means of menus. 12 13 3. Getting Started 3. Getting Started Disk Drives Inserting disks You may be using a single disk drive, a twin drive holding two Lift the flap at the front of the disk drive. Hold the disk label disks, or an even larger system. One of the drives is selected as upward, with the thumb of your right hand on the label. Push the Drive A, and this is the one that is always used unless you instruct disk gently into the drive and close the flap again. the computer to use another one. When you have only one disk drive, that drive is Drive A. Looking after your disks Now to insert a disk, but before you do so, please read the following. Disks should be handled with great care. Remember that successful operation depends on a piece of plastic rotating at high speed inside an envelope, so any physical damage is likely to i ncrease friction and may render the disk useless. Dust and grease on the magnetic surface can also be damaging. The read-write head of the disk drive actually touches the disk surface, and even a speck of dust can impair performance and cause reading errors. So always keep disks in their paper covers when not in use and never touch the magnetic surface. Similarly magnetic fields must be avoided. Never lay a disk on a If you have a single disk drive, insert your system disk into it. The television set, a tape recorder or a telephone, for example. system disk is the one provided with the disk drive and Ideally disks should be kept in a box designed for the purpose. It documentation, and which contains the information needed to all adds up to common sense: if disks are handled sensibly they make your disk system work correctly. If you have a dual disk will give good service over a long period. drive, insert the system disk into the left-hand (or topmost) drive ( Drive A). Of course, occasionally a disaster occurs: you leave a disk all night on a storage heater (after which it is slightly smaller and quite useless!) or you shut it in the latch of your briefcase. The only defence is to make back-up copies of your most valuable disks, and this will be dealt with in a later section.